Year: 2006
Type: article
Abstract: We have studied the magnetic behavior of dextran-coated magnetite (Fe3O4) nanoparticles with median particle size ⟨d⟩=8nm. Magnetization curves and in-field Mössbauer spectroscopy measurements showed that the magnetic moment MS of the particles was much smaller than the bulk material. However, we found no evidence of magnetic irreversibility or nonsaturating behavior at high fields, usually associated to spin canting. The values of magnetic anisotropy Keff from different techniques indicate that surface or shape contributions are negligible. It is proposed that these particles have bulklike ferromagnetic structure with ordered A and B sublattices, but nearly compensated the magnetic moments. The dependence of the blocking temperature with frequency and applied fields, TB(H,ω), suggests that the observed nonmonotonic behavior is governed by the strength of interparticle interactions.
Source: Journal of Applied Physics
DOI: 10.1063/1.2191471
Authors: E. Lima, A. L. Brandl, A. D. Arelaro, G. F. Goya
Institution: Universidade de São Paulo
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W1861223224